QoS with/without WebProxy

Hi again!.
I’m trying to setup QoS in my office with proxy enabled.

This is my actual config (primitive; only for test):

NAT

Flags: X - disabled, I - invalid, D - dynamic 
 0   ;;; Masquerade a la red local
     chain=srcnat action=masquerade src-address=192.168.1.0/24 
     out-interface=wan 

 1   ;;; Proxy
     chain=dstnat action=redirect to-ports=3128 protocol=tcp 
     src-address=192.168.1.0/24 in-interface=lan dst-port=80 

 2   chain=dstnat action=redirect protocol=tcp src-address=192.168.1.0/24 
     in-interface=lan dst-port=53 

 3   chain=dstnat action=redirect protocol=udp src-address=192.168.1.0/24 
     in-interface=lan dst-port=53 

 4   chain=dstnat action=redirect protocol=tcp src-address=192.168.1.0/24 
     in-interface=lan dst-port=123 

 5   chain=dstnat action=redirect protocol=udp src-address=192.168.1.0/24 
     in-interface=lan dst-port=123

MANGLE

Flags: X - disabled, I - invalid, D - dynamic 
 0   chain=postrouting action=mark-packet new-packet-mark=dnsFlow 
     passthrough=no protocol=icmp 

 1   chain=postrouting action=mark-packet new-packet-mark=httpFlow 
     passthrough=no protocol=tcp port=80,3128

QUEUE TREE

Flags: X - disabled, I - invalid 
 0   name="downstream" parent=lan limit-at=0 priority=8 max-limit=8M 
     burst-limit=0 burst-threshold=0 burst-time=0s 

 1   name="upstream" parent=wan limit-at=0 priority=8 max-limit=700k 
     burst-limit=0 burst-threshold=0 burst-time=0s 

 2   name="up interactivo" parent=upstream packet-mark=dnsFlow limit-at=100k 
     queue=default-small priority=1 max-limit=700k burst-limit=0 
     burst-threshold=0 burst-time=0s 

 3   name="up web" parent=upstream packet-mark=httpFlow limit-at=600k 
     queue=default-small priority=3 max-limit=700k burst-limit=0 
     burst-threshold=0 burst-time=0s 

 4   name="down interactivo" parent=downstream packet-mark=dnsFlow 
     limit-at=1024k queue=default-small priority=1 max-limit=8M burst-limit=0 
     burst-threshold=0 burst-time=0s 

 5   name="down web" parent=downstream packet-mark=httpFlow limit-at=0 
     queue=default-small priority=8 max-limit=8M burst-limit=0 
     burst-threshold=0 burst-time=0s

If proxy is disabled, then QoS will work ok. If proxy is enabled… aaagh!
See screenshots.

With proxy:

Without proxy:

Ummm… what’s wrong ?